Webb’s infrared view of the Southern Ring Nebula

Two views of Southern Ring Nebula by Webb
Click for original image.

The two images to the left were produced by the Webb Space Telescope, showing in false colors the Southern Ring Nebula as seen by two of Webb’s infrared cameras.

The two images shown here each combine near-infrared and mid-infrared data to isolate different components of the nebula. The image at [top] highlights the very hot gas that surrounds the central stars. The image at [bottom] traces the star’s scattered molecular outflows that have reached farther into the cosmos.

Based on the data, astronomers posit that up the system could have as many as five stars orbiting each other, with three as yet unseen, or the inner ones might no longer exist, having been absorbed by the bigger stars.

It’s possible more than one star interacted with the dimmer of the two central stars, which appears red in this image, before it created this jaw-dropping planetary nebula. The first star that “danced” with the party’s host created a light show, sending out jets of material in opposite directions. Before retiring, it gave the dim star a cloak of dust. Now much smaller, the same dancer might have merged with the dying star – or is now hidden in its glare.

A third partygoer may have gotten close to the central star multiple times. That star stirred up the jets ejected by the first companion, which helped create the wavy shapes we see today at the edges of the gas and dust. Not to be left out, a fourth star with an orbit projected to be much wider, also contributed to the celebration. It circled the scene, further stirring up the gas and dust, and generating the enormous system of rings seen outside the nebula. The fifth star is the best known – it’s the bright white-blue star visible in the images that continues to orbit predictably and calmly.

Much of this remains mere theory, based on the available data. Nonetheless, the data from many such planetary nebula continues to suggest their strange and wonderful shapes are created by multiple stars, acting as a mix-master to churn up the nebula’s dust.

Hubble captures 20-year fading of planetary nebula

The fading of the Stingray Nebula
Click for full image.

Astronomers using the Hubble Space Telescope have now tracked the spectacular fading of the Stingray Nebula, which when it was discovered in the mid-1990s was labeled the youngest such object ever found.

Astronomers have caught a rare look at a rapidly fading shroud of gas around an aging star. Archival data from NASA’s Hubble Space Telescope reveal that the nebula Hen 3-1357, nicknamed the Stingray nebula, has faded precipitously over just the past two decades. Witnessing such a swift rate of change in a planetary nebula is exceeding rare, say researchers.

Images captured by Hubble in 2016, when compared to Hubble images taken in 1996, show a nebula that has drastically dimmed in brightness and changed shape. Bright blue fluorescent tendrils and filaments of gas toward the center of the nebula have all but disappeared, and the wavy edges that earned this nebula its aquatic-themed name are virtually gone. The young nebula no longer pops against the black velvet background of the vast universe.

Astronomers have found that the central star had been heating precipitiously in the late 20th century, from 40K to 108K degrees Fahrenheit. Since then it has begun to cool. They think that flash of heat, caused by what they think was short period of helium fusion, caused the planetary nebula to brighten, and now fade.

New model suggests ringed nebula caused by star merger

The Blue Ring Nebula
Click for full image.

Based on a new theoretical model, astronomers now believe that the Blue Ring Nebula, a planetary nebula discovered in 2004 by the Galaxy Evolution Explorer (GALEX), was the result of the merger of two stars that only occurred a few thousand years earlier.

The image to the right, cropped, reduced, and annotated to post here, shows the original GALEX image on top, with a model to illustrate the geometry. The nebula is shaped like an hour-glass, with the rings the wide parts at the top and bottom. We just happen to be looking at it along its axis.

A new study published online on Nov. 18 in the journal Nature may have cracked the case. By applying cutting-edge theoretical models to the slew of data that has been collected on this object, the authors posit the nebula – a cloud of gas in space – is likely composed of debris from two stars that collided and merged into a single star.

While merged star systems are thought to be fairly common, they are nearly impossible to study immediately after they form because they’re obscured by debris the collision kicks up. Once the debris has cleared – at least hundreds of thousands of years later – they’re challenging to identify because they resemble non-merged stars. The Blue Ring Nebula appears to be the missing link: Astronomers are seeing the star system only a few thousand years after the merger, when evidence of the union is still plentiful. It appears to be the first known example of a merged star system at this stage.

When the merger happened it caused the bi-polar jets that formed the hourglass shape.

Two new multi-wavelength Hubble images of planetary nebulae

Hubble images of the Butterfly and Jewel Bug planetary nebulae
Click for full image.

Cool images from Hubble! Astronomers have used the Hubble Space Telescope’s entire suite of instruments to produce spectacular new multi-wavelength images of two planetary nebulae, stars that for some reasons not yet entirely understood are surrounded by breath-taking jets and cloud-formations of all shapes and sizes.

The two images are to the right, cropped and reduced to post here.

Planetary nebulas, whose stars shed their layers over thousands of years, can turn into crazy whirligigs while puffing off shells and jets of hot gas. New images from the Hubble Space Telescope have helped researchers identify rapid changes in material blasting off stars at the centers of two nebulas — causing them to reconsider what is happening at their cores.

In the case of NGC 6302, dubbed the Butterfly Nebula, two S-shaped streams indicate its most recent ejections and may be the result of two stars interacting at the nebula’s core. In NGC 7027, a new cloverleaf pattern — with bullets of material shooting out in specific directions — may also point to the interactions of two central stars. Both nebulas are splitting themselves apart on extremely short timescales, allowing researchers to measure changes in their structures over only a few decades.

This is the first time both nebulas have been studied from near-ultraviolet to near-infrared light, a complex, multi-wavelength view only possible with Hubble.

The press release suggests that the most likely and popular explanation for the formation of planetary nebula is the interaction of two closely orbiting stars. While this might be true, it remains only one theory among many, all of which explain some of what we see and none of which explain everything. As I noted in my November 2014 cover story about planetary nebulae for Sky & Telescope:
» Read more

Birth of a planetary nebula

Beginnings of a planetary nebula

Astronomers, using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile have created a multi-spectral radio image of a dying star in its very initial stages of becoming a beautiful planetary nebula.

[Using ALMA,] the team obtained a very detailed view of the space around W43A. “The most notable structures are its small bipolar jets,” says Tafoya, the lead author of the research paper published by the Astrophysical Journal Letters. The team found that the velocity of the jets is as high as 175 km per second, which is much higher than previous estimations. Based on this speed and the size of the jets, the team calculated the age of the jets to be less than a human life-span.

“Considering the youth of the jets compared to the overall lifetime of a star, it is safe to say we are witnessing the ‘exact moment’ that the jets have just started to push through the surrounding gas,” explains Tafoya. “The jets carve through the surrounding material in as little as 60 years. A person could watch their progress throughout their lifetime.”

Over time those jets, thought to be caused by the interaction of the central star with a smaller secondary star that orbits it, will interact increasingly with the surrounding gas. The result will be a quite spectacular planetary nebula.

New Hubble image of Red Rectangle

The Red Rectangle

Cool image time! I think the Red Rectangle might be my favorite planetary nebula. The new image on the right, taken by the Hubble Space Telescope, is the best yet of this weirdly shaped object. And it continues to suggest, as I noted whimsically in an article about it for Sky & Telescope back in November 2014, that this is a web being spin by the universe’s largest spider.

New Hubble image of Twin Jet Nebula

Twin Jet Nebula

Astronomers using the Hubble Space Telescope have taken a new image of the Twin Jet Nebula, a planetary nebula officially called PM M2-9.

The M in this name refers to Rudolph Minkowski, a German-American astronomer who discovered the nebula in 1947. The PN, meanwhile, refers to the fact that M2-9 is a planetary nebula. The glowing and expanding shells of gas clearly visible in this image represent the final stages of life for an old star of low to intermediate mass. The star has not only ejected its outer layers, but the exposed remnant core is now illuminating these layers — resulting in a spectacular light show like the one seen here. However, the Twin Jet Nebula is not just any planetary nebula, it is a bipolar nebula.

The bipolar nature of the nebula is thought to be caused by the interaction of a binary star system. I like to say that the orbiting stars act like the blades in a blender, mixing the ejected layers of material to produce the jets and shapes that make planetary nebula so beautiful.

Hubble first imaged this nebula in 1997. This image, using the telescope’s newer instruments, is important because it shows the complex layers within each jet, suggesting multiple ejection events in the past.

Hubble captures a necklace in space

necklace in space

Who needs aliens and imagined cities on the moon when you have a reality that produces such strange and beautiful things as the image on the right?

On July 2, the Hubble Space Telescope took this image of a planetary nebula, aptly dubbed the Necklace Nebula. As the caption explains,

A pair of stars orbiting close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate.

The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star’s equator, producing a ring. The embedded bright knots are dense gas clumps in the ring.

The binary still exists, and can be seen as the star in the center of the necklace. The two stars are now only a few million miles apart and complete an orbit around each other in about a day.